Scratch coat leveling attachment



J. G. WATTERS 3,041,946

SCRATCH COAT LEVELING ATTACHMENT July 3, 1962 Filed April 15, 1959 2Sheets-Sheet 1 INVENTOR.

Jamey G M ATTEES A rrozxvs July 3, 1962 J. G. WATTERS 3,041,946

SCRATCH COAT LEVELING ATTACHMENT 2 Sheets-Sheet 2 Filed April 13, 1959INVENTOR. (lower 6. )Marrnay i wx f.

A r roams-y FIG 2 United States Patent @fifice 7 3,0413% Patented July3, 1962 3,041,946 SCRATCH COAT LEVELING ATTACHlVIENT Jerry G. Watters,Cedar Rapids, Iowa, assignor to Iowa Manufacturing Company of CedarRapids, Cedar Rapids, Iowa, a corporation of Iowa Filed Apr. 13, 1959,Ser. No. 806,132 1 Claim. (Cl. 94-46) The present invention pertains tobituminous paving machines and more particularly to a levelingattachment for such machines.

Paving machines for laying bituminous road surfaces are well known inthe art and in wide use. The present invention is designed for that typeof machine in which the screed is trailed from the rear ends of twoscreed arms, which extend rearward on each side of the ma chine frompivots at their forward ends to the machine proper, so thatsubstantially the entire weight of the screed rests upon the bituminousmat.

When such a machine is used to construct an entirely new road, the newmat is applied to a road bed which has been graded beforehand so that itis relatively free of bumps, depressions and other irregularities. Whenthe machine is used, however, to resurface old concrete or other paving,the leveling or scratch coat is applied to a surface which is usuallyrough owing to wear, weather and other causes. No matter how carefullythe paving machine may be designed, bumps and irregularities in the oldsurface will nevertheless cause a certain amount of vertical movement ofthe forward pivot points of the screed arms which in turn will cause thescreed to impress a waviness to the scratch coat.

The present invention is designed to minimize the effect of such bumpsand irregularities upon the screed so that these irregularities will notbe transmitted to the scratch coat. For this purpose a pair of rigid,rearward extensions, removably secured to the screed arms, is employed,and across their trailing ends is connected :1 sled-like plate whichrides directly on the scratch coat itself. These extensions and theplate provide an additional point of suspension for the screed in such away that the effect of vertical movements of the forward pivot points ofthe screed arms upon the screed is greatly reduced. In addition, theplate, inasmuch as it trails the screed, tends to smooth out whateverirregularities in the old surface may nevertheless be relayed to thescratch coat. Various means for adjusting the rake and crown of theplate are also provided.

While the present invention is primarily useful when laying the scratchcoat upon old paving, yet it can, if desired, be employed when layingthe finish coats as well, or even in the construction of an entirely newroad upon a prepared road bed, although in such cases it is usually notnecessary.

Accordingly, the primary object of the present invention is theprovision of a leveling attachment for a paving machine which minimizesvertical deflection of the screed as the paver passes over a roughsurface.

An additional object of the present invention is to provide a pavingmachine screed leveling attachment incorporating rearward extensions ofthe screed arms and a supporting and leveling surface at the rear of thelatter and engaging the new mat surface.

Another object of the present invention is the provision in a pavingmachine leveling attachment of a plate engaging the new mat surfacerearward of the screed.

A further object of the present invention is to provide means in aleveling plate attachment for a paving machine to adjust the platerelative to the screed and to the new mat surface.

Other and further objects, features and advantages will be apparent fromthe description of the preferred form of the invention which follows,read in connection with the accompanying drawings, in which:

FIGURE 1 is a plan view of a paving machine with the leveling deviceattached thereto in operative position;

FIGURE 2 is a side elevation of a paving machine with the levelingdevice attached thereto in operative position; and FIGURE 3 is aperspective view of a portion of the leveling device.

In order to facilitate understanding of the invention reference is madeto the improvement thereof shown in the accompanying drawings anddetailed descriptive language employed. It will, nevertheless, beunderstood that no limitation of the invention is thereby intended andthat various changes and alterations are contemplated such as wouldordinarily occur to one skilled in the art to which the inventionrelates.

Referring now to the drawings, 10 designates generally a bituminouspaving machine of a well-known type provided on each side with crawlers11 driven by sprockets 12. Bogies 13 bear against crawlers 11 in theusual manner. The direction of movement of paver 10 when engaged inpaving is indicated by arrows adjacent FIG- URES 1 and 2. Accordingly,the terms forward, rearward," trailing and the like are used hereafterwith reference to such direction of movement. Screed arms 14 are pivotedat their forward ends at points 15, between sprockets 12, to frame 16 ofthe paving machine, and frame 16 in turn is carried in the usual manneron the crawler and sprocket assembly. Screed 17 is positioned in thecustomary manner between the rear ends of screed arms 14, and theinclination of screed 17 relative to the old road surface 18, by whichthe thickness of the mat 19 laid thereon is controlled, is adjusted byhand wheels and screws 20.

Screed arm extensions 30 extend rearwardly of screed arms 14- and arerigidly and removably attached to the rear ends of the latter inoverlapping relation by clamp plates and bolts 31 or equivalent means.Extensions 30 are provided with connecting brace 32 between and adjacentthe rear ends thereof. Forward of brace 32 two pairs of vertical hingeplates 33 are secured opposite one another on each extension 30 andextend downwardly therefrom. Adjusting arms 34 are pivoted at theirforward ends between respective pairs of hinge plates 33 by any suitablemeans, such as hinge pins 35, so that arms 34 are freely movablevertically thereabout. A second connecting brace 36 is secured betweenthe rear ends of arms 34 and hand wheels and screws 37 are threadedvertically through the rear ends of extensions 30 with their lower endssuitably secured to arms 34- so that rotation of screws 37 adjusts the:angle of arms 34 relative to extensions 30. Spaced along brace 32 andsecured thereto are screw jacks 38, to the lower end of which areattached casters 39. By turning handles 40 casters 3? can be lowered toor raised from contact with road surface 18 for transporting theleveling device when not in use.

The leveling sub-assembly comprises a leveling plate 50 having a smoothlower surface and upturned forward and trailing edges 51. Spacedinwardly from the ends of plate 5% and secured to the top surfacethereof are mounting blocks 52, to the tops of which in turn arefastened U-brackets 53. The latter are adapted to receive the lower endsof two pairs of vertical hinge plates 54 rigidly secured at their upperends to the trailing ends of arms 34. Hinge plates 54 are pivotallysecured to brackets 53 by hinge pins 55 so that plate 50 is therebyhinged about a transverse axis with respect to arms 34. Turnbuckles 56are provided between the forward ends of blocks 52 and the rear ends ofarms 34 to adjust the position of plate 50 about hinge pins 55 withrespect to the mat or scratch coat 19 laid by screed 17.

A crowning mechanism is incorporated by providing keyhole notches 60 inedges 51 midway between the ends of plate 59 to permit the latter to beflexed about the axis extending between notches 60. At each side of theaforesaid axis and longitudinal of plate 50 are adjusting levers 61hingedly secured to plate 50 through U-brackets 62 and links 63. Levers61 are provided along the upper portions adjacent their inner ends withU-brackets 64 between which is mounted turnbuckle 65. The construc tion,purpose and operation of the crowning mechanism is more fully shown anddescribed in U.S. Patent 2,914,994.

T use the device of the present invention, extensions 30 are secured toscreed arms 14 by clamp plates and bolts 31. Screed 17 is then adjustedin the usual manner by hand wheels 20 until a scratch coat 19 of properdepth is laid thereby. Paver is then continued forward until plate 56engages the new mat 19. At this point, casters 40 are withdrawn, byturning handle 4%, from any contact with road 18 and hand wheels 37 andturnbuckles 56 are adjusted so that plate 50 bears squarely and evenlyupon mat 19. Paver 16 is then moved ahead to lay the remainder of mat orscratch coat 19.

It will readily be understood that, despite the fact that pivot pointsof screed arms 1 are positioned between sprockets 12 on each side ofpaver 1t), bumps and dips in the old road is contacted by crawlers 11will nevertheless cause a certain amount of vertical deflection of pivotpoints 15 (see FIGURE 2). Plate 50, however, aifords an additional pointof suspension for screed 17 and tends therefore to minimize the effectof vertical deflections of pivot points 15 thereupon and thus also uponmat 19 laid thereby Plate 50 also acts to smooth out any waviness,which, though small, may nevertheless be imparted to the mat by verticalmovements of pivots 15. However, such waviness is usually so small thatit may be disregarded, and for this reason the area of the lower surfaceof plate 50 need be only large enough to provide a good loaddistribution upon the scratch coat or mat 19. Consequently, plate Stirin practice is often shorter than screed 17, to provide for whichextensions 30 are convergingly angled from the ends of screed arms 14 topoints just forward of hinge plates 33 (see FIGURE 1).

It will also be readily understood that the longer extensions 39 are,the more they will minimize the effect of any unevenness of the old roadsurface 18 upon screed 17. In practice, it has been found sufficient formost purposes if the distance between pivot points 15 and leveling plate50 is about twice that from pivot points 15 to screed 17. Hand wheels 37and turnbuckles 56 permit adjustment of plate 50 relative to screedsurface 17 so that no matter what may be the depth of the mat or scratchcoat 19 being applied, plate 50 can nevertheless be adjusted to rideevenly thereon. If a crown is i being imported by screed 17 to mat 19,adjustment of turnbuckle 65 will permit plate to be flexed or bowedabout the axis between notches to conform to the crown of the mat.

When paver 10 is to be transported with the leveling device attached,casters 39 are lowered by turning handles 4% so that plate 50 isprevented from striking the ground owing to pitching movements of frame16. Removing clamp plates and bolts 31 quickly and easily detaches thedevice and permits paver 16% to pave other surfaces not requiring theleveling attachment.

I claim:

In a paving machine of the kind described, including a pair of laterallyspaced screed arms pivoted at their forward ends to the side of themachine for vertical movement relative thereto, a screed assemblysupported by said screed arms and having a paving material applyingunder surface extending transversely of said screed arms, adjustablemeans between the trailing ends of said screed arms and the trailing endof said screed in order to alter the fore and aft inclination of saidsurface with respect to the roadway thereby also causing alteration ofthe elevation of said screed arms during operation of said machine, thecombination therewith of scratch coat leveling apparatus, said apparatuscomprising: a pair of laterally spaced leveling arms rigidly secured attheir forward ends to the trailing ends of said screed arms to formrigid rearward extensions thereof; a pair of laterally spaced adjustingarms pivoted at their forward ends adjacent the rear ends of saidleveling arms for vertical movement relative to said leveling arms, saidadjusting arms being relatively short compared to said leveling arms andextending rearwardly from said pivots to just beyond the rearward endsof said leveling arms; a screed leveling plate assembly carried by saidadjusting arms and having a surface adapted to slidably engage thesurface of the paving applied by said screed assembly and to support thelatter, said surface extending transversely of said adjusting arms andsaid plate assembly being pivoted about a transverse horizontal axisbetween and adjacent the rearward ends of said adjusting arms; and meansto permit independent and fine adjustment of said plate assemblyrelative both to said screed assembly and leveling arms in order tocompensate for said alterations in the elevation of said screed andleveling arms, said means including arm adjusting means operativebetween each of said leveling arm ends and their respective adjustingarms for adjustably positioning said adjusting arms and plate assemblyrelative to said leveling arms, and plate assembly adjusting means foradjustably positioning said plate assembly about said axis relative tosaid adiusting arms.

References Cited in the file of this patent UNITED STATES PATENTS2.847,917 I-leer et a1. Aug. 19, 1958 2,890,632 Madison et a1. June 16,1959 2,951,426 Pollitz Sept. 6, 1960

